Add refresh v3 draft implementation

Does not include migration for refreshing from v2 (currently on stable)

This PR branch only supports refreshing to/from mysql-router-k8s charm code with refresh v3

Author: carlcsaposs-canonical

actions.yaml

@@ -1,20 +1,59 @@
 # Copyright 2023 Canonical Ltd.
 # See LICENSE file for licensing details.
 
-resume-upgrade:
-  description: Upgrade remaining units (after you manually verified that upgraded units are healthy).
+pre-refresh-check:
+  description: Check if charm is ready to refresh
+force-refresh-start:
+  description: |
+    Potential of data loss and downtime
+    
+    Force refresh of first unit
+    
+    Must run with at least one of the parameters `=false`
   params:
-    force:
+    check-compatibility:
       type: boolean
-      default: false
+      default: true
       description: |
-        Potential of *data loss* and *downtime*
+        Potential of data loss and downtime
         
-        Force upgrade of next unit.
+        If `false`, force refresh if new version of PostgreSQL and/or charm is not compatible with previous version
+    run-pre-refresh-checks:
+      type: boolean
+      default: true
+      description: |
+        Potential of data loss and downtime
+        
+        If `false`, force refresh if app is unhealthy or not ready to refresh (and unit status shows "Pre-refresh check failed")
+    check-workload-container:
+      type: boolean
+      default: true
+      description: |
+        Potential of data loss and downtime during and after refresh
+        
+        If `false`, allow refresh to PostgreSQL container version that has not been validated to work with the charm revision
+  required: []
+resume-refresh:
+  description: |
+    Refresh next unit(s) (after you have manually verified that refreshed units are healthy)
+    
+    If the `pause_after_unit_refresh` config is set to `all`, this action will refresh the next unit.
+    
+    If `pause_after_unit_refresh` is set to `first`, this action will refresh all remaining units.
+    Exception: if automatic health checks fail after a unit has refreshed, the refresh will pause.
+    
+    If `pause_after_unit_refresh` is set to `none`, this action will have no effect unless it is called with `check-health-of-refreshed-units` as `false`.
+  params:
+    check-health-of-refreshed-units:
+      type: boolean
+      default: true
+      description: |
+        Potential of data loss and downtime
+        
+        If `false`, force refresh (of next unit) if 1 or more refreshed units are unhealthy
         
-        Use to
-        - force incompatible upgrade and/or
-        - continue upgrade if 1+ upgraded units have non-active status
+        Warning: if first unit to refresh is unhealthy, consider running `force-refresh-start` action on that unit instead of using this parameter.
+        If first unit to refresh is unhealthy because compatibility checks, pre-refresh checks, or workload container checks are failing, this parameter is more destructive than the `force-refresh-start` action.
   required: []
 
 set-tls-private-key:

charm_version

@@ -51,7 +51,7 @@ parts:
     source: .
     after:
       - poetry-deps
-    poetry-export-extra-args: ['--only', 'main,charm-libs']
+    poetry-export-extra-args: ['--only', 'main,charm-libs', '--without-hashes'] # TODO: re-enable hashes
     build-packages:
       - libffi-dev  # Needed to build Python dependencies with Rust from source
       - libssl-dev  # Needed to build Python dependencies with Rust from source
@@ -86,16 +86,9 @@ parts:
     build-packages:
       - git
     override-build: |
-      # Workaround to add unique identifier (git hash) to charm version while specification
-      # DA053 - Charm versioning
-      # (https://docs.google.com/document/d/1Jv1jhWLl8ejK3iJn7Q3VbCIM9GIhp8926bgXpdtx-Sg/edit?pli=1)
-      # is pending review.
-      python3 -c 'import pathlib; import shutil; import subprocess; git_hash=subprocess.run(["git", "describe", "--always", "--dirty"], capture_output=True, check=True, encoding="utf-8").stdout; file = pathlib.Path("charm_version"); shutil.copy(file, pathlib.Path("charm_version.backup")); version = file.read_text().strip(); file.write_text(f"{version}+{git_hash}")'
-
+      # TODO: set charm version in refresh_versions.toml
       craftctl default
     stage:
       - LICENSE
-      - charm_version
-      - workload_version
       - scripts
       - templates

charmcraft.yaml

@@ -15,3 +15,11 @@ options:
       and managed by the charm.
     type: string
     default: "{}"
+
+  pause_after_unit_refresh:
+    description: |
+      Wait for manual confirmation to resume refresh after these units refresh
+
+      Allowed values: "all", "first", "none"
+    type: string
+    default: first

config.yaml

@@ -46,11 +46,8 @@ requires:
 peers:
   cos:
     interface: cos
-  upgrade-version-a:
-    # Relation versioning scheme:
-    # DA056 - Upgrading in-place upgrade protocol
-    # https://docs.google.com/document/d/1H7qy5SAwLiCOKO9xMQJbbQP5_-jGV6Lhi-mJOk4gZ08/edit
-    interface: upgrade
+  refresh-v-three:
+    interface: refresh
   mysql-router-peers:
     interface: mysql_router_peers
 resources: